The present invention relates to a mobile communication system having a radio network controller for controlling the communication quality between a mobile terminal and a radio base station.
Along with popularization of the Internet, the number of users who access the Internet using mobile terminals is increasing. Conventionally, for a fixed network, Diffserv for priority control (K. Nichols, et al., “Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers”, IETF RFC2474, December 1998) or RSVP for bandwidth reservation (R. Ed, et al., “Resource ReSerVation Protocol (RSVP) Version 1 Functional Specification”, IETF RFC2205, September 1997) has been examined to satisfy the communication quality requested by users.
In a mobile communication system, however, the communication quality requested by users cannot be satisfied only by priority control or bandwidth reservation. The communication quality in a mobile communication system largely depends on the error rate in a radio zone. As a method of reducing the error rate in the radio zone, retransmission control or an error correcting code is used. When retransmission control or an error correcting code is used, a necessary bandwidth widens. When the necessary bandwidth is ensured as a predetermined width in the communication bandwidth of a radio channel, the utilization efficiency of the radio channel cannot be improved.